Technical Field
The disclosure generally relates to a positioning device, a positioning system, a positioning method, and a computer-readable medium for detecting the position of a terminal.
Description of the Related Art
GPS (Global Positioning System) is used in the open air for measuring the position or the movement locus of a communication terminal. However, it is often difficult to use GPS indoors or in an urban area where there are many tall buildings, and a method capable of realizing inexpensive and high-speed positioning (measurement of the position or the movement locus) indoors by using an information terminal is being developed.
To detect the position of a mobile communication terminal indoors, a system may include a wireless device such as a wireless LAN (Local Area Network), a mobile phone, or RFID (Radio Frequency IDentification). For example, in some systems, a communication terminal may receive an identifier transmitted from a stationary transmission device, and the position of the communication terminal may be detected by the identifier being returned to the stationary transmission device.
Additional techniques may determine whether the distance between a position indicated by a positioning result and position(s) indicated by at least one past positioning result(s) is equal to or less than a threshold, and may evaluate the positioning reliability based on the determined.
However, although the positioning reliability is evaluated based on the distance determined with respect to the past positioning information, the evaluation may assume that the location of a communication terminal is reliable, and the evaluation may not consider that the location of a communication terminal is falsified. Further, in some systems, a terminal may falsify its position by transmitting, to a positioning server, an identifier of a stationary transmission device that is installed at another location, which is not actually received.